这些箱子里 都是什么
“What's inside all these crates?”
THE DIALOGUE REEL
这么多箱子
“So many crates.”
这些箱子里 都是什么
“What's inside all these crates?”
是刑道司
“They're archives”
Direct spoken expression in this communicative setting.
In spoken Chinese, '都' is almost obligatorily inserted before the predicate when referring to plural objects like '这些箱子' to stress completeness.
LEARNING CHUNKS & PARTICLES
what are all of these
Used with '都' to emphasize collective curiosity about a group or collection of items.